Process for dewaxing oil



Patented Feb. 8, 1938 UNITED STATES rnocnss non nnwexme on.

Maner L. -Wade, Long Beach, Calif., assignor to Union Oil Company ofCalifornia, Los Angeles, Oalii'., a corporation of California NoDrawing. ,Application April it, 1937, Serial No. 137,583

4 Claims. (Cl. 204-24) This invention relates to the electricalseparation of wax from wax-bearing oil and particularly to aids andaccelerators to dewaxing waxbearing oil by electrodeposition orelectroplating,

5 and is a continuation in part of my copending application Serial No.89,119, filed July 6, 1936, which is a division of application SerialNo. 745,167 filed September 22, 1934.

In. the processes for dewaxing oil electrically the wax-bearing oil ismixed with a suitable diluent, chilled toa temperature at which wax "isprecipitated out of solution as a finely divided wax suspension and thewax suspension removed from; the mixture by electrodeposition upon elec-1 trically charged electrodes. In most cases the wax precipitates formedin unrefined oils are comprised of negatively charged wax crystals orparticles and are deposited or plated in a solid cake or layer upon thepositive electrode under 20 the influence of an electric field.

Objects of this invention are to increase the rate and emciency ofdewaxing wax-bearing oil by electrodeposition methods.

It has been found that the rate of electrodepo- 25 sition can beincreased by the addition to the oil or oil'diluent mixture prior tochilling and electrical treatment, certain extraneous substances whichact as promoters or accelerators. It is believed that these substances,upon chilling, may be co precipitated with the wax to be removed fromthe oil, and that the effect of the co-precipitated substance upon thewax is favorable to electrodeposition.

tillate with added extraneous aids to electrodeposition as follows. Thewax-bearing lubricating oil distillate was first diluted with 50 volumepercent of light hydrocarbon distillate having a boiling point range ofapproximately 326 to 395 F., then a small quantity of an accelerator wasadded to the oil-diluent solution and the mixture chilled to atemperature at which wax precipitated from solution in the form of afine suspension. This mixture was subsequently subjected to a.unidirectional electric field between oppositely charged, fiat plate,immersed electrodes having areas of 8 square inches and spaced inchapart from face to face. Under the influence of the unidirectionalelectric field the precipitated wax was removed from the wax-bearingmixture as a deposit or plated layer upon the positive electrode. Blanktests were simultaneously made in the same manner and under identicalconditions but without 'the accelerators being added, in order todetermine the relative rates of electrodeposition with and without thesaid accelerator. Table I indicates the conditions of the hereinbeforedescribed tests.

It was discovered that the accelerators when added to the waxy oilsolution at temperatures at or below the cloud point of the solution,were ineffective to increase the rate of wax deposition while those-sameaccelerators when added at a temperature above the cloud pointwereefiective in increasing the rate of electrodeposition. Theelectrodeposition accelerators listed hereinafter in Table I weretherefore added to the waxy oildiluent solutions at temperatures of 120?F. or

35 For example, a number of dewaxing tests were higher, which weretemperatures well above the run on Santa Fe springs raw lubricating oildiscloud point of the 01] solutions.

Table I 40 D g Mien v u Deposit Test Temp. 0 Electrodeposition No. F.accelerator t on electrodes Grams Percent minutes increase 45 1 7 5234,600 None. 70 0.5 o I. G. S. wax. 210 300 r 0.5 I. G. E. wax. 186 2662 6 60 30,600 None. 78

0.5% beeswax (purified). 200 266 3 7 52 34,500 None. 70 0.5% Mouton wax165 238 (crude). 50 4 7 to 31,500 None. 89 0.6% carnauba wax. 202 5 6 5134,200 None. 88 0.5% I. G. O. P. wax. 180 205 a 1o 51 34,350 None. 9a0.6% steal-inc pitch. 171 184 7 6 49 30,600 None. 78 55 0.5% I. G. B.wax. 139 179 8 10 60 34,2)0 None. 113 0.4% calcium stearate. 174 154 Wera... s:

. a eesp a l0 10 48 33,000 None. 121

0.2% formic acid. 177 146 -lieved to contain montanic, melissic,carnaubic,

cerotic and other fatty acids of the general formula CnHilnOZ, highmolecular weight alcohols and esters of these acids and alcohols.

The I. G. O. P., I. G. B., I. G. E. and I. G. S. waxes are standardproducts of the I. G. Farbenindustrie Aktiengesellschaft. Albino asphaltcomprises an acid treated naphtha extract of a 300 F. melting pointcracked residuum. It has a melting point of approximately F.

In Table II is found a list of the physical characteristics of theaccelerators appearing in Table I, and the class of chemicalcompositions to trodeposition under the influence of an electric currentor electric field.

This invention also resides in the hereinbefore describedelectrodeposition dewaxing aids and the employment thereof as aids tothe process of electrodeposition of wax from wax-bearing oil.

The accelerators or promoters to-electrodeposition have been foundeffective when used in conjunction with various oil solvents anddiluents such as liquid propane, gasoline, benzene, kerosene, carbontetrachloride, and lubricating oil fractions.

An example of the practical application of the invention is as follows:

The wax-bearing oil to be dewaxed is mixed under pressure with asuitable diluent such as liquid propane in the approximate proportion ofi one part oil to two parts liquidpropane by volume at a temperaturewell above the cloud point of the solution which may be approximately100 F. An electrodeposition accelerator such as I. G. S. wax is added tothe warm oil-propane solution in a small quantity ranging between 0.2%to 0.5% of the volume of the oil. The solution containing theaccelerator is self-chilled by reduction which they. are each believedto be related.-

Table II Electrodeposition 5: 2 0

p. M. P. F. Chemical composition M No. No. (UbbeL) I G. 0 P. wax 13. 8113 219 Esters of montanic acid. I G. B wax 57. 8 148 177. 5 Esters ofmontanic acid. I G. E. wax 14.3 142 166 Esters of montanic acid. I. G.S. wax 143. 0 170 181 Esters of montanic acid. Montan wax (refined) 64.0 67 Contains montanic acid. Montan wax (crude)... 26. 0 92 183 Containsmoutunic acid. Carnauba wax 4. 0 71 184 Esters of carnaubic acid.Beeswax 20. 0 91 147 Contains melissic and cerotic A-grade asphalt (d)209-260 Petroleum pitch or residue. Calcium stearate (c) Insolublemetallic soap. Formic acid (I) 47. 5 Organic acid-40% aq. sol. Stearinepitch Fatty acid.

(a) Acid number (neutralization number) by the A. S. '1. M. testD-186-27'l. 7

Eb; Sap. No.-Saponiflcatien number by the A. S. T. M. test DAM-28.

c M. P.Melting point, Ubbelohde.

(d) 23-30% fixed carbon 7595% sol. in CO1; ductility 0. sp. gr. 1.09.

(e) Insoluble in water. 801. in alcohol. Forms colloidal suspension inoil.

(I) B. 1. 100.8 0. sp. gr. 1.218. I

Substances which have been found to produce the most pronouncedpromotion or acceleration of the rate of the electrodeposition of waxesfrom suspension in wax-bearing oils are therefore believed to be of thefollowing classes:

1. Waxes which contain high molecular weight alcohols, montanic acid,carnaublc acid, melissic acid and esters thereof.

2. Petroleum asphalts, residues or pitches or extracts thereof.

3. Fatty acid bottoms or pitch.

4. Metallic soaps such as calcium stearate.

5. Organic acids.

6. Aromatic compounds such as naphthalene a-bromonaphthalene andp-dichlordiphenyl.

'7. Aromatic nitrogen compounds such as nitro= benzene, pyridine andaniline.

8. Phenolic compounds such as cresol, sodium phenoxide andp-aminophenol.

9. Petroleum residues, pitches or extracts thereof such as A-gradeasphalt or albino as- Dhalt.

This invention resides in a process for increasing the rate ofelectrodeposition of precipitated wax from wax-bearing oil whereinextraneous electrodeposition aids are added to the waxbearing oil priorto chilling and the subsequently precipitated wax resulting fromchilling the mixture or solution removed from the oil byelecprecipitated wax, which is in most cases charged negatively, movesunder the influence of the electric field between the electrodes and isdeposited in, a solid layer or coating on the surface of the positivelycharged electrode.

The positive electrode plates after receiving a coating of wax may beremoved from the oil solution and the wax subsequently removed therefromby suitable mechanical means.

The quantity of wax deposited upon the electrode in a given period oftime from the oil solution containing an accelerator is found to be.

increased to as much as 300% over that which is deposited upon theelectrode under similar conditions but without the presence of the added8.0- V

It is to be understood that the foregoing is merely illustrative of onemethod of operation and that the invention is not limited thereby butmay include other methods to accomplish the same within the scope of theinvention.

I claim:

1. A process for dewaxing oil comprising adding to the wax-bearing oilan electrodeposition accelerator belonging to the group of fatty acidsconsisting of montanic, carnaubic, melissic, cerotic and stearic acids,chilling the oil to precipitate wax and removing the wax from themixture by electrodeposition.

2. A processior .dewaxing oil comprising adding montanic acid to thewax-bearing oil, chilling the wax-bearing oil to precipitate wax andremoving the wax irom the mixture by electrodeposition.

3. A process for dewaxing oil comprising adding carnaubic acid to thewax-bearing oil, chilling the wax-bearing oil to precipitate wax andremoving the wax from the mixture by electrodeposition.

4. A process for dewaxing oil comprising adding stearic acid to thewax-bearing oil, chilling the wax-bearing oil to precipitate wax andremoving the wax from the mixture by electrodeposition.

' MANER L. WADE.

